【求源码解析】pullRefresh()方法为什么能实现scroll()初始化功能

看了一下pullRefresh的源码，发现好像没有调用scroll()的方法
pullRefresh的几个init
mui.init pulldownRefresh

init: function(element, options) {  
            this._super(element, $.extend(true, {  
                scrollY: true,  
                scrollX: false,  
                indicators: true,  
                deceleration: 0.003,  
                down: {  
                    height: 50,  
                    contentinit: '下拉可以刷新',  
                    contentdown: '下拉可以刷新',  
                    contentover: '释放立即刷新',  
                    contentrefresh: '正在刷新...'  
                },  
                up: {  
                    height: 50,  
                    auto: false,  
                    contentinit: '上拉显示更多',  
                    contentdown: '上拉显示更多',  
                    contentrefresh: '正在加载...',  
                    contentnomore: '没有更多数据了',  
                    duration: 300  
                }  
            }, options));  
        },  
        _init: function() {  
            this._super();  
            this._initPocket();  
        },

pullRefresh 5+

init: function(element, options) {  
                this.element = element;  
                this.options = options;  
                this.wrapper = this.scroller = element;  
                this._init();  
                this._initPulldownRefreshEvent();  
            },  
            _init: function() {  
                var self = this;  
                //document.addEventListener('plusscrollbottom', this);  
                window.addEventListener('dragup', self);  
                document.addEventListener("plusscrollbottom", self);  
                self.scrollInterval = window.setInterval(function() {  
                    if (self.isScroll && !self.loading) {  
                        if (window.pageYOffset + window.innerHeight + 10 >= document.documentElement.scrollHeight) {  
                            self.isScroll = false; //放在这里是因为快速滚动的话，有可能检测时，还没到底，所以只要有滚动，没到底之前一直检测高度变化  
                            if (self.bottomPocket) {  
                                self.pullupLoading();  
                            }  
                        }  
                    }  
                }, 100);  
            },

想给pullRefresh添加一个和scroll().destroy()方法，应该怎么加？